Culiacan:
A tanker truck transporting fuel collided with a passenger bus in the northwestern state of Sinaloa, killing 21 people, local officials have said.
Investigators are trying to determine what caused the crash, which took place just before midnight Friday on the Pacific coast near the border with Nayarit state.
A source at Sinaloa's prosecutors office told AFP that 19 people died in the crash, and two more died later in a local hospital.
The victims included two minors and eight women, the source said.
Local press reported that the truck was transporting more than 20,000 litres (4,400 gallons) of fuel in two tanks. One of the tankers apparently broke loose and rolled downhill, slamming into the oncoming bus.
"We fear that there are whole families among the victims," the source said.
Ten bus passengers were wounded, including a six year-old boy.
The victims included farmers who were heading to Nayarit state looking for work, officials said.